This invention relates to a machine and a method for packaging fiber material.
This invention can be advantageously be applied to the packaging of fiber material, preferably loose tobacco, to which this description will hereinafter refer but without thereby limiting the scope of the invention.
The packs which the tobacco is inserted into generally comprise a pouch-like containing portion which is sealed along a line transversal to the axis of symmetry of the pack, and a flap which protrudes from the open side of the pouch and which can be folded over the containing portion in such a way as to guarantee a better seal and protection for the contents of the pack.
The pouch, which is sealed to hold in the tobacco aroma, also has suitable opening/closing systems designed to keep it well sealed at all times and to prevent the tobacco from deteriorating and losing its aroma as a result of oxidation and exposure to humidity and air.
In prior art machines for packaging loose tobacco, suitably treated and measured tobacco portions are fed in an ordered succession to a book-like device designed to press the mass of tobacco before inserting it into the packs.
The tobacco portions drop into the device, which is substantially a press which folds closed temporarily in book-like fashion on the mass of tobacco. Basically, the device reduces the dimensions of the tobacco. In effect, during this operation, the tobacco is pressed and immediately pushed into the pack.
A pusher element channels the tobacco into the pack, which is held open vertically under the compacting device, and further compresses the tobacco into it.
The pusher element then withdraws to allow sealing means to close the pack.
Alternatively, the packs are rested on a rotary carousel having a plurality of locations where the packs are held and filled with a measured quantity of tobacco.
The open packs are fed to the carousel, the tobacco is placed on the open flap and suitable carrier elements, located along the path followed by the rotary unit, insert the tobacco into the packs.
Next, the carousel passes through a sealing station where the packs are closed.
The solutions adopted by the prior art have some disadvantages.
In particular, the production lines currently in use present stretches on which the tobacco advances freely, without being controlled or guided. The stretches where the mass of tobacco is gravity fed inevitably slow down the production process waiting for the tobacco to fall.
Also, during gravity feed, the smallest, volatile particles of tobacco tend to scatter, causing material to be lost and leading to weight errors in the quantity of tobacco actually inserted into the packs.
Another major drawback is linked to the way the packs are sealed. In other words, during the step of inserting the tobacco into the pack, specific elements push the tobacco to the bottom of the pack, simultaneously compressing it, and then withdraw, tending to drag some of the fibers of material away with them.
The fibers that are dragged away from the mass of tobacco when the pushing element withdraws are trapped in the sealing line.
This inevitably means a waste of tobacco but more than that, reduces the quality of the packed tablet as a whole.
In effect, the seal is no longer uniform but presents small gaps along the seal which can no longer guarantee the optimum conditions for preserving the tobacco.
Through these gaps, the tobacco gradually loses parts of its flavor and aroma, is constantly exposed to humidity and is oxidized by the air.
Thus, from the time it is packaged to when it is sold, the tobacco inevitably deteriorates, which means the product sold is of poorer quality.